N = int(input())
c = input()

num_red = c.count('R')
print(num_red - c[:num_red].count('R')) N = int(input()) N int(input()) int input() input c = input() c input() input num_red = c.count('R') num_red c.count('R') c.count c count 'R' print(num_red - c[:num_red].count('R')) print num_red - c[:num_red].count('R') num_red c[:num_red].count('R') [:num_red].count [:num_red] c :num_red num_red count 'R' N = int(input()) int(input()) N num_red = c.count('R') c.count('R') num_red c = input() input() c
N = int(input())
c = input()

num_red = c.count('R')
print(num_red - c[:num_red].count('R'))